Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 9865B8F5 for ; Tue, 10 Nov 2015 17:09:09 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-pa0-f49.google.com (mail-pa0-f49.google.com [209.85.220.49]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id DDED918C for ; Tue, 10 Nov 2015 17:09:08 +0000 (UTC) Received: by pacdm15 with SMTP id dm15so2288391pac.3 for ; Tue, 10 Nov 2015 09:09:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-type; bh=zlFur4n/0B6eLomAxYY62X+7zd8ptgD3U5vyHe+LmjY=; b=fONFnjQ4veTAgUvjwBZ7/OK4Y3Q/QjmPPCueE8ljcwSP0mL0UbN+MBAi27W8j2y2zL NWIwhhEBJ23nYgQ5yg5RPaQxgjAZ1/7gn0W4DY7KFWAMV2dJJiMfPj7a4QB4+sx4Swgd zDolZn2vPKtuvhJMh/K7DR4c32GENt2qIICEUFJXMwwDYK0hg8KsvUBGopVJYeMDDAG/ w7yvsYnc5tAGGtlqWjXM4UsSQ+4BRFKV/8p+MAnBzb4Tqj9NXdYmxC/kUj6d1imTICZT NZlDCDOVILRHh+jT5wEoVL8kQH5CHXMXXmuU+EziYhICeEmY1FB2z7QWyVgmlcs3I64s +cjQ== X-Received: by 10.68.223.226 with SMTP id qx2mr7125087pbc.157.1447175348558; Tue, 10 Nov 2015 09:09:08 -0800 (PST) Received: from [192.168.0.132] (S0106bcd165303d84.cc.shawcable.net. [96.54.102.88]) by smtp.googlemail.com with ESMTPSA id zk3sm5105417pbb.41.2015.11.10.09.09.07 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 10 Nov 2015 09:09:07 -0800 (PST) To: bitcoin-dev@lists.linuxfoundation.org References: <5640F172.3010004@gmail.com> <20151109210449.GE5886@mcelrath.org> <5642172C.701@gmail.com> From: Peter Tschipper X-Enigmail-Draft-Status: N1110 Message-ID: <564224B2.9090903@gmail.com> Date: Tue, 10 Nov 2015 09:09:06 -0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------070208000204040609060805" X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] request BIP number for: "Support for Datastream Compression" X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Nov 2015 17:09:09 -0000 This is a multi-part message in MIME format. --------------070208000204040609060805 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 10/11/2015 8:46 AM, Jeff Garzik via bitcoin-dev wrote: > Comments: > > 1) cblock seems a reasonable way to extend the protocol. Further > wrapping should probably be done at the stream level. agreed. > > 2) zlib has crappy security track record. > Zlib had a bad buffer overflow bug but that was in 2005 and it got a lot of press at the time. It's was fixed in version 1.2.3...we're on 1.2.8 now. I'm not aware of any other current issues with zlib. Do you have a citation? > 3) A fallback path to non-compressed is required, should compression > fail or crash. agreed. > > 4) Most blocks and transactions have runs of zeroes and/or highly > common bit-patterns, which contributes to useful compression even at > smaller sizes. Peter Ts's most recent numbers bear this out. zlib > has a dictionary (32K?) which works well with repeated patterns such > as those you see with concatenated runs of transactions. > > 5) LZO should provide much better compression, at a cost of CPU > performance and using a less-reviewed, less-field-tested library. I don't think LZO will give as good compression here but I will do some benchmarking when I can. > > > > > > On Tue, Nov 10, 2015 at 11:30 AM, Tier Nolan via bitcoin-dev > > wrote: > > > > On Tue, Nov 10, 2015 at 4:11 PM, Peter Tschipper > > wrote: > > There are better ways of sending new blocks, that's certainly > true but for sending historical blocks and seding transactions > I don't think so. This PR is really designed to save > bandwidth and not intended to be a huge performance > improvement in terms of time spent sending. > > > If the main point is for historical data, then sticking to just > blocks is the best plan. > > Since small blocks don't compress well, you could define a > "cblocks" message that handles multiple blocks (just concatenate > the block messages as payload before compression). > > The sending peer could combine blocks so that each cblock is > compressing at least 10kB of block data (or whatever is optimal). > It is probably worth specifying a maximum size for network buffer > reasons (either 1MB or 1 block maximum). > > Similarly, transactions could be combined together and compressed > "ctxs". The inv messages could be modified so that you can > request groups of 10-20 transactions. That would depend on how > much of an improvement compressed transactions would represent. > > More generally, you could define a message which is a compressed > message holder. That is probably to complex to be worth the > effort though. > > > >> >> On Tue, Nov 10, 2015 at 5:40 AM, Johnathan Corgan via >> bitcoin-dev > > wrote: >> >> On Mon, Nov 9, 2015 at 5:58 PM, gladoscc via bitcoin-dev >> > > wrote: >> >> >> I think 25% bandwidth savings is certainly >> considerable, especially for people running full >> nodes in countries like Australia where internet >> bandwidth is lower and there are data caps. >> >> >> ​ This reinforces the idea that such trade-off decisions >> should be be local and negotiated between peers, not a >> required feature of the network P2P.​ >> >> >> -- >> Johnathan Corgan >> Corgan Labs - SDR Training and Development Services >> http://corganlabs.com >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >> >> >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > > > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev --------------070208000204040609060805 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit
On 10/11/2015 8:46 AM, Jeff Garzik via bitcoin-dev wrote:
Comments:

1) cblock seems a reasonable way to extend the protocol.  Further wrapping should probably be done at the stream level.
agreed.

2) zlib has crappy security track record.

Zlib had a bad buffer overflow bug but that was in 2005 and it got a lot of press at the time.  It's was fixed in version 1.2.3...we're on 1.2.8 now.  I'm not aware of any other current issues with zlib. Do you have a citation?

3) A fallback path to non-compressed is required, should compression fail or crash.
agreed.

4) Most blocks and transactions have runs of zeroes and/or highly common bit-patterns, which contributes to useful compression even at smaller sizes.  Peter Ts's most recent numbers bear this out.  zlib has a dictionary (32K?) which works well with repeated patterns such as those you see with concatenated runs of transactions.

5) LZO should provide much better compression, at a cost of CPU performance and using a less-reviewed, less-field-tested library.
I don't think LZO will give as good compression here but I will do some benchmarking when I can.






On Tue, Nov 10, 2015 at 11:30 AM, Tier Nolan via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:


On Tue, Nov 10, 2015 at 4:11 PM, Peter Tschipper <peter.tschipper@gmail.com> wrote:
There are better ways of sending new blocks, that's certainly true but for sending historical blocks and seding transactions I don't think so.  This PR is really designed to save bandwidth and not intended to be a huge performance improvement in terms of time spent sending.
If the main point is for historical data, then sticking to just blocks is the best plan.

Since small blocks don't compress well, you could define a "cblocks" message that handles multiple blocks (just concatenate the block messages as payload before compression). 

The sending peer could combine blocks so that each cblock is compressing at least 10kB of block data (or whatever is optimal).  It is probably worth specifying a maximum size for network buffer reasons (either 1MB or 1 block maximum).

Similarly, transactions could be combined together and compressed "ctxs".  The inv messages could be modified so that you can request groups of 10-20 transactions.  That would depend on how much of an improvement compressed transactions would represent.

More generally, you could define a message which is a compressed message holder.  That is probably to complex to be worth the effort though.

 

On Tue, Nov 10, 2015 at 5:40 AM, Johnathan Corgan via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
On Mon, Nov 9, 2015 at 5:58 PM, gladoscc via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
 
I think 25% bandwidth savings is certainly considerable, especially for people running full nodes in countries like Australia where internet bandwidth is lower and there are data caps.
​ This reinforces the idea that such trade-off decisions should be be local and negotiated between peers, not a required feature of the network P2P.​
 

--
Johnathan Corgan
Corgan Labs - SDR Training and Development Services

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https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev




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https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev



_______________________________________________
bitcoin-dev mailing list
bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev




_______________________________________________
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https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

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